The present invention relates to a flame-spraying material and in particular a flame-spraying material for repairing, by flame-spraying, any damaged part of a furnace or kiln such as a coke oven and the like where a number of heating-and-cooling cycles are carried out.
Recently, repair of coke ovens by flame-spraying has been effected and outstanding effects have been demonstrated in relation to the repair time, the adhesive strength of the repaired part, durability and the like. It has been known to employ a flame-spraying material comprised of about 70%SiO.sub.2, said flame spraying material having a refractiveness of 1100.degree. C. to 1280.degree. C.
Coke ovens are lined with silica bricks having a coefficient of thermal expansion that rapidly increases between 300.degree. C. and 500.degree. C. and keeps a level without significant increase temperatures in excess of 500.degree. C. For this reason, the silica bricks have a very high resistance to thermal spalling where they are used at temperatures over 500.degree. C. However, if the silica bricks are repaired, once they are damaged, with a flame-spray material comprising approximately 70% by weight of SiO.sub.2, no adequate endurance can be achieved at present as a result of the peeling off of the flame-sprayed coating due to the differences in the hot expansion behavior between the base silica bricks and the flame-sprayed coating which causes significant thermal stress therebetween as the flame-sprayed coating linearly expands thermally, contrary to silica bricks, up to about 1000.degree. C.